• You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.

TRAM D300 driver bias problem

smokie4

Member
Jul 23, 2008
8
0
11
I have just aquired a D300, and the output was low on SSB, although it would go from a 2W DK to 6W in AM mode. SSB was peaking at 6W also. I checked the 2166 and the 1969 transistors initially and found both had readings from C to E. Tested 2 new ones and compared and the new ones didn't have the reading. Installed both the new 2166 and the 1969 in the radio and tried to set the driver bias. The not so good Service manual I got from fleabay states the current should be 30mA. The lowest I can get is 105mA. I checked the varister or what ever they are and they are not shorted and read good with the diode tester and ohm meter. Also checked TR38, TR40 which seem to be inline with the driver and final section and they test good on my cheep transistor checker. The capacitors in the circuit also seem to test OK.
The 2166 driver is a replacement for the 2SC1306 I've heard so that's what I used as the suspect driver was already a 2166 when I received the radio.
Receiver section seems to be working exceptionally.
Any help would sure be appreciated.
 

bias problems

Evisently I was a victim of counterfit 2166 and 1969 transistors from fleabay. I had some real deal's and put them in and it all lined up. I do still have a problem with low output on SSB.
I noticed in the TR25 it has VR7 tied to it for the ALC. Also C141 according to the schematic and the SM parts list, is supposed to be a ceramic 0.0047 cap. It has in it's place an electrolytic 2.2mfd that is of the Uniden brand. I don't know if this is part of the problem or not. I don't want to keep changing things around without prior knowledge.

thanks
 
buying discontinued parts on ebay is a crapshoot at best.
as soon as i read this i thought counterfiets.
 

dxChat
Help Users
  • No one is chatting at the moment.